The long term objective of this study is to determine the value of adding treatment programs like the Challenging Horizons Program (CHP) to the services available to youth with ADHD in a community. There continues to be a lack of data on effective psychosocial treatments for adolescents with ADHD. This is problematic, as medication is inadequate for most youth as a sole form of treatment and adolescence is a time where the impairment associated with ADHD becomes increasingly dangerous, life-altering, and serious. Specifically, this study aims to: 1) Evaluate the efficacy of the after-school program model and the consultation model of CHP as compared to each other and as compared to community care, 2) Estimate cost-effectiveness ratios for each of the two levels of services, and 3) Identify moderators and mediators of treatment response for the two CHP intervention models. In addition, the findings should inform treatment decisions about which children need which level of care. Treatment services are delivered either through an after-school program (CHP-AS) or through teachers employed by the school who are trained and provided with ongoing consultation on the CHP methods (CHP-C). Over five years 315 participants who meet criteria for ADHD will be recruited at seven middle schools across two sites and randomly assigned to receive either the CHP-AS, CHP-C or community care. Costs of providing the services for all three conditions will be measured as well as symptom and impairment outcomes. Data collection will occur on an ongoing basis over the academic year of a child's participation in the project. In addition, formal evaluations will occur at baseline, immediately post-treatment, and 6 months post-treatment. Consistent with findings from preliminary studies it is expected that response to both active treatment conditions will vary across participants. Assessments will be collected that identify potential moderators and mediators of treatment response and these will be included in the analyses in order to identify child and parent characteristics that may predict response to treatment as well as variables related to the treatment process (e.g., attendance) that predicts response. PUBLIC HEALTH RELEVANCE: The lack of adequate treatments for youth with problems related to substance use, automobile accidents, school failure and other difficulties associated with adolescents with ADHD presents a serious public health problem. This study evaluates the effectiveness and cost associated with two emerging comprehensive treatment options for youth and identifies characteristics of the teens (moderators) and the treatment (mediators) that predict positive outcomes. The development of a cost-effective treatment for young adolescents with ADHD that can be integrated into schools and the community will provide invaluable assistance to the public health field and address problems across multiple sectors of public well being.